[Changes of neurobehavioral functions in workers exposed to manganese]

The aim of this study was to assess the neurotoxic effects associated with the level of airborne manganese in the work place. A cumulative exposure index(CEI) was calculated for each subject. The neurobehavioral test battery, in terms of choosing reaction time, finger tapping, digit symbol, stylus in hole, Benton visual retention and Santa Ana dexterity was applied in the study. The manganese exposed workers had slower motor and response speed, poorer visuomotor coordination and steadiness. There was a dose-response relationship tendency between the cumulative exposure index and the behavioral function. Hence the neurobehavioral test may be a sensitive method in detecting early changes in motor and cognitive function among manganese-exposed workers. The study also demonstrates that the cumulative exposure of manganese about 1 mg/m3 per year may induce subclinical signs of intoxication.